v.

1. reveal unintentionally;
   bewray
   
   • Her smile betrayed her true feelings
2. deliver to an enemy by treachery;
   sell
   
   • Judas sold Jesus
   • The spy betrayed his country
3. disappoint, prove undependable to; abandon, forsake;
   fail
   
   • His sense of smell failed him this time
   • His strength finally failed him
   • His children failed him in the crisis
4. be sexually unfaithful to one's partner in marriage;
   cheat on, cheat, cuckold, wander
   
   • She cheats on her husband
   • Might her husband be wandering?
5. give away information about somebody;
   denounce, tell on, give away, rat, grass, shit, shop, snitch, stag
   
   • He told on his classmate who had cheated on the exam
6. cause someone to believe an untruth;
   deceive, lead astray
   
   • The insurance company deceived me when they told me they were covering my house